Journal of Bacteriology最新文献

{"title":"GlnA3<i>_Mt</i> is able to glutamylate spermine but it is not essential for the detoxification of spermine in <i>Mycobacterium tuberculosis</i>.","authors":"Sergii Krysenko, Carine Sao Emani, Moritz Bäuerle, Maria Oswald, Andreas Kulik, Christian Meyners, Doris Hillemann, Matthias Merker, Gareth Prosser, Inken Wohlers, Felix Hausch, Heike Brötz-Oesterhelt, Agnieszka Mitulski, Norbert Reiling, Wolfgang Wohlleben","doi":"10.1128/jb.00439-24","DOIUrl":"10.1128/jb.00439-24","url":null,"abstract":"<p><p><i>Mycobacterium tuberculosis</i> is well adapted to survive and persist in the infected host, escaping the host's immune response. Since polyamines such as spermine, which are synthesized by infected macrophages, are able to inhibit the growth of <i>M. tuberculosis</i>, the pathogen needs strategies to cope with these toxic metabolites. The actinomycete <i>Streptomyces coelicolor</i>, a close relative of <i>M. tuberculosis,</i> makes use of a gamma-glutamylation pathway to functionally neutralize spermine. We therefore considered whether a similar pathway would be functional in <i>M. tuberculosis</i>. In the current study, we demonstrated that <i>M. tuberculosis</i> growth was inhibited by the polyamine spermine. Using <i>in vitro</i> enzymatic assays we determined that GlnA3<i>_Mt</i> (Rv1878) possesses genuine gamma-glutamylspermine synthetase catalytic activity. We further showed that purified His-Strep-GlnA3<i>_Mt,</i> as well as native GlnA3<i>_Mt,</i> prefer spermine as a substrate over putrescine, cadaverine, spermidine, or other monoamines and amino acids, suggesting that GlnA3<i>_Mt</i> may play a specific role in the detoxification of the polyamine spermine. However, the deletion of the <i>glnA3</i> gene in <i>M. tuberculosis</i> did not result in growth inhibition or enhanced sensitivity of <i>M. tuberculosis</i> in the presence of high spermine concentrations. Gene expression analysis of spermine-treated <i>M. tuberculosis</i> revealed no difference in the level of <i>glnA3_Mt</i> expression relative to untreated cells, whereas a gene encoding a previously characterized efflux pump (Mmr; <i>rv3065</i>) was significantly upregulated. This suggests that bacterial survival under elevated spermine concentrations can not only be achieved by detoxification of spermine itself but also by mechanisms resulting in decreased spermine levels in the bacteria.</p><p><strong>Importance: </strong>Upon <i>Mycobacterium tuberculosis</i> infection macrophages synthesize the polyamine spermine, which at elevated concentrations is toxic for <i>M. tuberculosis</i>. Based on our investigations of spermine resistance in the closely related actinomycete <i>Streptomyces coelicolor</i>, we hypothesized that the glutamylspermine synthetase GlnA3 may be responsible for the resistance of <i>M. tuberculosis</i> against toxic spermine. Here we show that GlnA3_<i>Mt</i> can indeed covalently modify spermine via glutamylation. However, GlnA3_<i>Mt</i> is probably not the only resistance mechanism since a <i>glnA3</i> null mutant of <i>M. tuberculosis</i> can survive under spermine stress. Gene expression studies suggest that an efflux pump may participate in resistance. Thus a combination of GlnA3_<i>Mt</i> and specific efflux pumps acting as putative spermine transporters may constitute an active spermine-detoxification system in <i>M. tuberculosis</i>.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0043924"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841054/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143065833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Screening a library of temperature-sensitive mutants to identify secretion factors in <i>Staphylococcus aureus</i>.","authors":"Owen Leddy, Amany M Ibrahim, Muhammad S Azam, Sadie Solomon, Wenqi Yu, Olaf Schneewind, Dominique Missiakas","doi":"10.1128/jb.00433-24","DOIUrl":"10.1128/jb.00433-24","url":null,"abstract":"<p><p>Protein secretion is an essential cell process in bacteria, required for cell envelope biogenesis, export of virulence factors, and acquisition of nutrients, among other important functions. In the Sec secretion pathway, signal peptide-bearing precursors are recognized by the SecA ATPase and pushed across the membrane through a translocon channel made of the proteins SecY, SecE, and SecG. The Sec pathway has been extensively studied in the model organism <i>Escherichia coli</i>, but the Sec pathways of other bacteria such as the human pathogen <i>Staphylococcus aureus</i> differ in important ways from this model. Unlike in <i>E. coli</i>, a subset of precursors in <i>S. aureus</i> contains a YSIRK/GXXS (YSIRK) motif in an extended signal peptide. These proteins are secreted into the cross-wall compartment bounded by invaginating septal membranes during cell division. To gain insights into the factor(s) and mechanism(s) enabling protein secretion and spatial specificity in <i>S. aureus</i>, we isolated and screened a collection of temperature-sensitive (<i>ts</i>) mutants. These efforts identified at least one <i>secA(ts</i>) allele as well as mutations in the <i>secG</i> and <i>pepV</i> genes. A SecA pull-down experiment identified SecDF, all ribosomal proteins, several chaperones and proteases, as well as PepV, validating the genetic screen in identifying candidate cofactors of SecA in <i>S. aureus</i>.IMPORTANCEAll organisms use the Sec pathway for protein secretion, and key components of this pathway are essential for viability. The discovery of conditional loss-of-function mutants played an important role in defining the genetic basis of protein secretion in model organisms. In turn, the identification of Sec components facilitated mechanistic studies and revealed general rules for protein secretion but did not answer species-specific intricacies. Gram-positive bacteria, such as <i>Staphylococcus aureus</i>, restrict the secretion of some proteins into the septal membranes that bind their division site at mid-cell. Here, we screen a library of conditional temperature-sensitive mutants to define components of the Sec pathway of <i>S. aureus</i> and factors that may regulate its activity.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0043324"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841065/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143005772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent progress in proteins regulating the germination of <i>Bacillus subtilis</i> spores.","authors":"Tianyu Zhang, Ziqi Gong, Bing Zhou, Lei Rao, Xiaojun Liao","doi":"10.1128/jb.00285-24","DOIUrl":"10.1128/jb.00285-24","url":null,"abstract":"<p><p>Bacterial spores can remain dormant for years, but they maintain the ability to recommence life through a process termed germination. Although spore germination has been reviewed many times, recent work has provided novel conceptual and molecular understandings of this important process. By using <i>Bacillus subtilis</i> as a model organism, here we thoroughly describe the signal transduction pathway and events that lead to spore germination, incorporating the latest findings on transcription and translation that are likely detected during germination. Then, we comprehensively review the proteins associated with germination and their respective functions. Notably, the typical germinant receptor GerA and the SpoVAF/FigP complex have been newly established as channels for ions release at early stage of germination. Moreover, given that germination is also affected by spore quality, such as molecular cargo, we collect the data about the proteins regulating sporulation to affect spore quality. Specifically, RocG-mediated glutamate catabolism during sporulation to ensure spore quality; GerE-regulated coat protein expression, and CotH-modified coat protein by phosphorylation to ensure normal coat assembly; and RNase Y-degraded RNA in newly released spores to promote dormancy. The latest progress in our understanding of these germination proteins provides valuable insights into the mechanism underlying germination.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0028524"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841064/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142949347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LitR and its quorum-sensing regulators modulate biofilm formation by <i>Vibrio fischeri</i>.","authors":"Brittany L Fung, Karen L Visick","doi":"10.1128/jb.00476-24","DOIUrl":"10.1128/jb.00476-24","url":null,"abstract":"<p><p>Quorum sensing controls numerous processes ranging from the production of virulence factors to biofilm formation. Biofilms, communities of bacteria that are attached to one another and/or a surface, are common in nature, and when they form, they can produce a quorum of bacteria. One model system to study biofilms is the bacterium <i>Vibrio fischeri</i>, which forms a biofilm that promotes the colonization of its symbiotic host. Many factors promote <i>V. fischeri</i> biofilm formation <i>in vitro</i>, including the symbiosis polysaccharide (SYP) and cellulose, but the role of quorum sensing is currently understudied. Recently, a quorum-sensing-dependent transcription factor, LitR, was shown to negatively influence <i>V. fischeri</i> biofilm formation in the context of a biofilm-overproducing strain. To better understand the importance of LitR, we identified conditions in which the impact of LitR on biofilm formation could be observed in an otherwise wild-type strain and then investigated its role and the roles of upstream quorum regulators in biofilm phenotypes. In static conditions, LitR and its upstream quorum regulators, including autoinducer synthases LuxS and AinS, contributed to control over biofilms that were both SYP and cellulose dependent. In shaking liquid conditions, LitR and AinS contributed to control over biofilms that were primarily cellulose dependent. LitR modestly inhibited cellulose transcription in a manner that depended on the transcription factor VpsR. These findings expand our understanding of LitR and the quorum-sensing pathway in the physiology of <i>V. fischeri</i> and illuminate negative control mechanisms that prevent robust biofilm formation by wild-type <i>V. fischeri</i> under laboratory conditions.IMPORTANCEQuorum sensing is a key regulatory mechanism that controls diverse phenotypes in numerous bacteria, including <i>Vibrio fischeri</i>. In many microbes, quorum sensing has been shown to control biofilm formation, yet in <i>V. fischeri</i>, the link between quorum sensing and biofilm formation has been understudied. This study fills that knowledge gap by identifying roles for the quorum sensing-controlled transcription factor, LitR, and its upstream quorum-sensing regulators, including the autoinducer synthases AinS and LuxS, in inhibiting biofilm formation under specific conditions. It also determined that LitR inhibits the transcription of genes required for cellulose biosynthesis. This work thus expands our understanding of the complex control over biofilm regulation.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0047624"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841056/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143059166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural characterization of pyruvic oxime dioxygenase, a key enzyme in heterotrophic nitrification.","authors":"Shuhei Tsujino, Yusuke Yamada, Miki Senda, Akihiko Nakamura, Toshiya Senda, Taketomo Fujiwara","doi":"10.1128/jb.00342-24","DOIUrl":"10.1128/jb.00342-24","url":null,"abstract":"<p><p>Nitrification by heterotrophic microorganisms is an important part of the nitrogen cycle in the environment. The enzyme responsible for the core function of heterotrophic nitrification is pyruvic oxime dioxygenase (POD). POD is a non-heme, Fe(II)-dependent enzyme that catalyzes the dioxygenation of pyruvic oxime to produce pyruvate and nitrite. To analyze the catalytic mechanism of POD, the crystal structure of POD from <i>Alcaligenes faecalis</i> (AfPOD) was determined at 1.76 Å resolution. The enzyme is a homotetramer, and the subunit structure is homologous to those of class II aldolases, in particular, a zinc-dependent L-fuculose-1-phosphate aldolase. The active site of the subunit is located at the bottom of a cleft formed with an adjacent subunit. The iron ion at the active site is coordinated by three histidines and three water molecules in an octahedral geometry. The putative oxygen tunnel was connected between the active site and the central cavity of the tetramer. The N-terminal region of AfPOD, which is essential for catalytic activity, is disordered in the crystal. Structure prediction with AlphaFold2 combined with mutational experiments suggested that the disordered N-terminal region adopts an α-helix conformation and participates in the formation of the active site. The catalytic mechanism of the dioxygenase reaction by POD is discussed on the basis of the molecular docking model.IMPORTANCEOur knowledge of nitrification has increased considerably in recent decades with the discovery of new nitrifying microorganisms and the characterization of their biochemical processes. Some heterotrophic bacteria and fungi are known to show nitrification activities, but the molecular mechanisms have been poorly understood. Here, we performed a structural characterization of pyruvic oxime dioxygenase (POD), a key enzyme in heterotrophic nitrification that produces nitrite from ammonia using pyruvic oxime as an intermediate. Structural and enzymatic analyses revealed that POD is a unique dioxygenase with features such as an aldolase backbone, an N-terminal α-helix, and an oxygen tunnel. Our results provide insights not only into the molecular mechanisms but also into the design of specific inhibitors of heterotrophic nitrification.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0034224"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841055/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142949361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel polysaccharide in the envelope of <i>S. aureus</i> influences the septal secretion of preproteins with a YSIRK/GXXS motif.","authors":"Amany M Ibrahim, Dominique Missiakas","doi":"10.1128/jb.00478-24","DOIUrl":"10.1128/jb.00478-24","url":null,"abstract":"<p><p>Bacteria transport proteins across the plasma membrane to assemble their envelope, acquire nutrients, and establish appropriate interactions with their environment. The majority of these proteins are synthesized as precursors with a cleavable N-terminal signal sequence for recognition by the Sec machinery. In <i>Staphylococcus aureus</i>, a small subset of secreted precursors carries a YSIRK/GXXS motif. This motif provides a pre-translocation function by promoting the targeting of precursors to septal membranes, but the <i>trans-</i>acting factors that regulate such spatial distribution are not known. Here, we used immunofluorescence-microscopy to compare the spatial trafficking of Staphylococcal protein A (SpA), an abundant YSIRK/GXXS bearing precursor, between mutants of an arranged transposon library. This genetic search identified a cluster of five genes predicted to encode enzymes responsible for the synthesis of a novel surface polymer referred to as Staphylococcal surface carbohydrate, Ssc. Mutants in the <i>ssc</i> gene cluster no longer restrict the secretion of SpA into the cross-walls of <i>S. aureus. ssc</i> mutants replicate like wild-type bacteria unless grown in phosphate-limited conditions, and do not contribute to virulence when examined in a mouse model of bloodstream infection. Together, our observations suggest that <i>S. aureus</i> may encode a minor, phosphate-free carbohydrate, and propose a possible assembly pathway for this polymer.</p><p><strong>Importance: </strong>Gram-positive bacteria assemble peptidoglycan-linked polymers known as wall teichoic acids (WTA). Both <i>Staphylococcus aureus</i> and <i>Bacillus subtilis</i> elaborate WTAs made of poly-glycerol or poly-ribitol phosphates. WTAs contribute to cell shape maintenance, cation homeostasis, and resistance to antimicrobial compounds. Yet, <i>B. subtilis</i> replaces its phosphate-rich polymer with minor teichuronic acids whose functions remain elusive. <i>S. aureus</i> also encodes a minor wall polymer that may be required for growth under phosphate-limited condition. Here, we find that this polymer could help define the composition of the septal compartment, the site of cell division also used to recruit preproteins with a YSIRK/GXXS motif. Thus, the envelope of <i>S. aureus</i> may be more complex than previously thought with minor wall polymers contributing some discrete functions.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0047824"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841062/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143052538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gut phages and their interactions with bacterial and mammalian hosts.","authors":"Marshall Godsil, Nathaniel L Ritz, Siddarth Venkatesh, Alexander J Meeske","doi":"10.1128/jb.00428-24","DOIUrl":"10.1128/jb.00428-24","url":null,"abstract":"<p><p>The mammalian gut microbiome is a dense and diverse community of microorganisms that reside in the distal gastrointestinal tract. In recent decades, the bacterial members of the gut microbiome have been the subject of intense research. Less well studied is the large community of bacteriophages that reside in the gut, which number in the billions of viral particles per gram of feces, and consist of considerable unknown viral \"dark matter.\" This community of gut-residing bacteriophages, called the gut \"phageome,\" plays a central role in the gut microbiome through predation and transformation of native gut bacteria, and through interactions with their mammalian hosts. In this review, we will summarize what is known about the composition and origins of the gut phageome, as well as its role in microbiome homeostasis and host health. Furthermore, we will outline the interactions of gut phages with their bacterial and mammalian hosts, and plot a course for the mechanistic study of these systems.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0042824"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11844821/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143023438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The GacS/GacA two-component system strongly regulates antimicrobial competition mechanisms of <i>Pseudomonas fluorescens</i> MFE01 strain.","authors":"Charly A Dupont, Yvann Bourigault, Héloïse Biziere-Maco, Amine M Boukerb, Xavier Latour, Corinne Barbey, Julien Verdon, Annabelle Merieau","doi":"10.1128/jb.00388-24","DOIUrl":"10.1128/jb.00388-24","url":null,"abstract":"<p><p><i>Pseudomonas fluorescens</i> MFE01 is an environmental bacterium characterized by an hyperactive type 6 secretion system (T6SS) and a strong emission of volatile organic compounds (VOCs). In a previous study, a transposition mutant, 3H5, exhibited an inactive T6SS and altered VOC emission. In 3H5, the interruption of <i>trpE</i> gene by the transposon was insufficient to explain these phenotypes. To determine the actual impact of this insertion, a comparative transcriptomic analysis was performed on the two-component system GacS/GacA, known to influence numerous phenotypes in <i>Pseudomonas</i>. The results demonstrated that the <i>gacS</i> gene is less expressed in 3H5 than in MFE01. Phenotypic analysis of a <i>gacS</i> deletion mutant, Δ<i>gacS</i>, confirmed many similarities between Δ<i>gacS</i> and 3H5. Indeed, Δ<i>gacS</i> exhibited an inactive T6SS and an altered VOC emission profile. In-depth analysis of volatilomes and phenotypes correlated with the decrease in <i>gacS</i> transcription, highlighting that the emission of 1-undecene is under the strict control of GacS/GacA. This study confirms that 1-undecene is not the sole volatile molecule responsible for MFE01's inhibition of <i>Legionella</i>. Moreover, MFE01 has antimicrobial activity against the phytopathogenic oomycetes <i>Phytophthora infestans</i> via hydrogen cyanide (HCN) emission, which is also controlled by GacS. In MFE01, GacS/GacA is also a partial positive regulator of other VOC emission, whose reduced emission in 3H5 coincides with the decrease in <i>gacS</i> transcription.</p><p><strong>Importance: </strong>Our model strain <i>Pseudomonas fluorescens</i> MFE01 uses an active type VI secretion system (T6SS) and volatile compounds (VCs) to outcompete other microorganisms in the natural environment. By investigating the cellular mechanism regulating the production of these weapons, we identified the two-component system GacS/GacA. Indeed, GacS cellular membrane sensor plays a crucial role in regulating T6SS activity and VC emission. Among the latter, 1-undecene and hydrogen cyanide are strong aerial inhibitors of the <i>Legionella</i> human pathogen and the <i>Phytophtora infestans</i> major plant pest, respectively. The aim is to improve the understanding of the regulation of these volatile molecule emission and the critical role of a global regulator in both plant and human health.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0038824"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841057/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143023463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LD-transpeptidase-mediated cell envelope remodeling enables developmental transitions and survival in <i>Coxiella burnetii</i> and <i>Legionella pneumophila</i>.","authors":"Dipak Kathayat, Yujia Huang, Joee Denis, Benjamin Rudoy, Hana Schwarz, Jacob Szlechter","doi":"10.1128/jb.00247-24","DOIUrl":"10.1128/jb.00247-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;&lt;i&gt;Coxiella burnetii&lt;/i&gt; and &lt;i&gt;Legionella pneumophila&lt;/i&gt; are two phylogenetically related bacterial pathogens that exhibit extreme intrinsic resistance when they enter into a dormancy-like state. This enables both pathogens to survive extended periods in growth-limited environments. Survival is dependent upon their ability to undergo developmental transitions into two phenotypically distinct variants, one specialized for intracellular replication and another for prolonged survival in the environment and host. We currently lack an understanding of the mechanisms that mediate these developmental transitions. Here, we performed peptidoglycan (PG) glycoproteome analysis and showed significant enrichment of PG structures catalyzed by LD-transpeptidases (LDTs) in the survival variants of &lt;i&gt;C. burnetii&lt;/i&gt; and &lt;i&gt;L. pneumophila&lt;/i&gt;. This is supported by the upregulation of LDTs, resulting in susceptibility to carbapenem antibiotics. Furthermore, deletion of the most upregulated LDT, &lt;i&gt;lpg&lt;/i&gt;1386, in &lt;i&gt;L. pneumophila&lt;/i&gt; significantly changes PG architecture, survival, and susceptibility to antibiotics. Significantly regulated by RpoS, a stationary-phase sigma factor, LDT-dependent PG remodeling is differentially activated by the host intracellular growth environment compared to axenic culture. In addition, β-barrel tethering, a newly discovered mechanism of LDT-mediated cell envelope stabilization, seems not to be specific to the survival variants. Interestingly, an outer membrane (OM) long-chain fatty acid transporter (Lpg1810) is tethered to PG in &lt;i&gt;L. pneumophila&lt;/i&gt;. Collectively, these findings show that LDT-mediated PG remodeling is a major determinant of developmental transitions and survival in &lt;i&gt;C. burnetii&lt;/i&gt; and &lt;i&gt;L. pneumophila&lt;/i&gt;. Understanding this mechanism might inform new therapeutic approaches for treating chronic infections caused by these pathogens, as well as suggest new methods to decontaminate environmental reservoirs during outbreaks.IMPORTANCE&lt;i&gt;Coxiella burnetii&lt;/i&gt; and &lt;i&gt;L. pneumophila&lt;/i&gt; cause Q Fever and Legionnaire's disease in humans, respectively. There is a lack of effective treatments for fatal chronic infections caused by these pathogens, particularly chronic Q Fever. These bacteria survive long term in nutrient-limited environments by differentiating into phenotypically distinct survival variants. Our study revealed that LDTs, a group of PG remodeling enzymes, play a prominent role in the phenotypic differentiations of these bacteria. We show that LDT-targeting carbapenems are effective against the survival variants, thus demanding the exploration of carbapenems for treating chronic infections caused by these pathogens. We report the tethering of a unique OM fatty acid transporter to PG in &lt;i&gt;L. pneumophila&lt;/i&gt; that could indicate a novel function of tethering, that is, the uptake of nutrient substrates. Homologs of this transporter are widely present in the Methylobacteriaceae family of bacteria kn","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0024724"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841132/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143023388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functions of nitroreductases in mycobacterial physiology and drug susceptibility.","authors":"Ifeanyichukwu E Eke, Robert B Abramovitch","doi":"10.1128/jb.00326-24","DOIUrl":"10.1128/jb.00326-24","url":null,"abstract":"<p><p>Tuberculosis is a respiratory infection that is caused by members of the <i>Mycobacterium tuberculosis</i> complex, with <i>M. tuberculosis</i> (Mtb) being the predominant cause of the disease in humans. The approval of pretomanid and delamanid, two nitroimidazole-based compounds, for the treatment of tuberculosis encourages the development of more nitro-containing drugs that target Mtb. Similar to the nitroimidazoles, many antimycobacterial nitro-containing scaffolds are prodrugs that require reductive activation into metabolites that inhibit the growth of the pathogen. This reductive activation is mediated by mycobacterial nitroreductases, leading to the hypothesis that these nitroreductases contribute to the specificity of the nitro prodrugs for mycobacteria. In addition to their prodrug-activating activities, these nitroreductases have different native activities that support the growth of the bacteria. This review summarizes the activities of different mycobacterial nitroreductases with respect to their activation of different nitro prodrugs and highlights their physiological functions in the bacteria.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0032624"},"PeriodicalIF":2.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11841060/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142949345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}